If statements based on url

I'm attempting to show a div tag based on the root url of my site i.e. if the url is dev.foo.com display div开发者_StackOverflow if else www.foo.com don't display etc. I've come up with this

<?php if (substr($_SERVER['REQUEST_URI'], 0, 5) !== 'dev.') {
    echo '<div class="dev-site-stuff">THIS IS THE DEV SITE!!</div>';
}
 ?>

But it isn't working and I can't see a reason - any thoughts greatly appreciated!

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you should use $_SERVER['SERVER_NAME']

If you have any other doubts just do a print_r($_SERVER); to actually see how the array is composed

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$url = explode('.', $_SERVER['HTTP_HOST'], 2);

/* you might want pretty variable that exactly gets the subdomain.
 * $subdomain = $url[0] != "www" ? $url[0] : "";
 * if($subdomain == "dev") {
 *   // dev site...
 * }else if($subdomain == "") {
 *   // www site...
 * }
 */

if($url[0] == "dev") {
  echo '<div class="dev-site-stuff">THIS IS THE DEV SITE!!</div>';
}

substr, strpos etc. are not always effective in this cases. It's nice?

EDIT: By the way read comments of your question.

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As well as @yes123 answer above you are also comparing a substring of length 5 against a string of length 4 so it will never be true.

You con use strrpos like this

 if (strrpos($_SERVER['SERVER_NAME'], 'dev.') > 0) {

Hope this helps.